The present invention relates to the impact consolidation of powders and, more particularly, to processes for enhancing the bond strength between deposited powders and a substrate.
The impact consolidation process, and particularly cold spray, can be used to adhesively bond powders to a substrate or to cohesively bond powders together. A concern when adhesively bonding powders to a substrate is that the bond strength of the deposited powder to the existing substrate be strong enough to prevent any disjoinment. A concern when cohesively bonding powders together is that the powder deposit be dense enough and particle to particle bonding be high enough such that the resulting powder deposit has the desired material properties.
Approaches exist in the prior art relating to the use of the impact consolidation process in conjunction with shot peening. Shot peening is a process whereby solid particles are propelled at a high velocity by means of a carrier gas or fluid and impact a target surface. This impact with the target surface is known to cause desirable stress properties. Prior methodologies teach the use of shot peening as a means to increase the density of deposited powders. Some of these approaches disclose the use of shot peening post powder deposition to increase the density of the deposit, including for example, U.S. Pat. No. 8,113,025 issued to Tapphorn et al. Other approaches disclose the use of shot peening simultaneous to powder deposition to also increase the density of the powder deposit, including for example, U.S. Pat. No. 3,754,976 issued to Babecki et al.